Vibration and MPG question

[kasper]

This being my 1st post on this forum, I am expecting that I am going to get flamed, but here goes anyways.

I have a '03 Expedition Eddie Baur Edition with the 5.4L. I just reached a little over 59K. I had my stock tires changed a couple hundred miles to the Firestone Destination A/T at the stock size. No complaints so far on it. My alignment is pretty good and I am sitting at the owner's manual psi recommendation of 35. I recently noticed when I brake that I have a slight vibration in the steering wheel. There is no pulling to the right or left either. I was thinking of taking them back to have them balanced again. Any ideas or recommendation of what is going on?

My second issue is on the MPG. I knew from the beginning that the MPG wasn't anything to brag about with our SUV's. I bought this with full purpose of towing trailers and heading off road in a few places. Before I changed my tires I noticed that I was getting less miles per gallon. I was averaging about 12 - 14 mpg depending on the situation. I thought that having some new tread would help me get back up, but currently I am in the 9 - 10 range. I have taken the recommendations I have read on here about staying below the 2K rpm when driving. I am pretty easy on the throttle. Usually on the highway at 2k rpm I can coast between 70 - 75 mph, but I usually stay around 65 - 70. I haven't yet gone into the dealership for the 60K maintenance. Would the 60K maintenance play a big factor on this? My truck is completely stock and I have read other options that can help, but I wanted to check to see if I am having problems in other areas to cause this significant drop. Thanks

I would appreciate any comment or assistance.

 

[lakmflx]

There's a few things that come to mind.

Check air filter, if dirty replace.

Check throttle body and MAF sensor for gunk and clean if needed

How do the spark plugs look?

O2 sensors working alright?

Theres alot more but these are the genral basics for MPG issues.

If nobody else posts some more things i can go into depth on what you should look for, but theres alot of informative members so im sure someone else will chime in.

 

[JUST4FUN]

the vibration sounds like warped rotors
make sure that the tires have the properly inflated
i go by the side wall psi

 

[kasper]

Originally posted by lakmflx
There's a few things that come to mind.

Check air filter, if dirty replace.

Check throttle body and MAF sensor for gunk and clean if needed

How do the spark plugs look?

O2 sensors working alright?

Theres alot more but these are the genral basics for MPG issues.

If nobody else posts some more things i can go into depth on what you should look for, but theres alot of informative members so im sure someone else will chime in.

Thanks for the heads up. Hopefully this weekend I will be get the time to look at some of these items. Unfortunately, being in SoCal next to the fires and being in the Marine Corps, my personal time is slightly limited.

 

[kasper]

Originally posted by JUST4FUN
the vibration sounds like warped rotors
make sure that the tires have the properly inflated
i go by the side wall psi

After reading most of the post, most say to run what Ford recommendations are. Also I just had my rear rotor turned when I had the oil changed at 50,0000, but I know they didn't do the front. I will have them looked out when I go in for the 60K. Thanks.

 

[JUST4FUN]

the reason i run what it says on the side wall is ford makes the truck not the tires IIRC Fierstone and ford had a problem with tires and inflation my explorer said to inflate to 26psi, Know I'm not a rocket scientest(sp) but thats 9 psi under what it said
on the side wall. I would think this would cause a problem
hence the tire recall. I ran three sets of the recalled tires(but at 35psi what the side wall said) with noproblems IMHO Ford not the tires were at fault.

 

[kasper]

Originally posted by JUST4FUN
the reason i run what it says on the side wall is ford makes the truck not the tires IIRC Fierstone and ford had a problem with tires and inflation my explorer said to inflate to 26psi, Know I'm not a rocket scientest(sp) but thats 9 psi under what it said
on the side wall. I would think this would cause a problem
hence the tire recall. I ran three sets of the recalled tires(but at 35psi what the side wall said) with noproblems IMHO Ford not the tires were at fault.

Well the Firestones I have say MAX 44 PSI. I am thinking of bumping it up to 40 when it is cold so when it warms up it should be running close to 44.

 

[Remo]

The sidewall psi is MAX psi. Do not inflate to this level, its not safe. These measurements are for cold tires. So if you inflate to the max at cold temperatures, when you are driving, the air in the tire heats up and the pressure increases. That's why this is unsafe. Additionally, the ride will be much stiffer at higher temperatures.

If you are running stock sizes, go by what is recommended by Ford. It should be in the manual or on the door jam. This is the safest, most appropriate pressure and will give the best performance and comfort.

If all else fails, in my experience, car tires are usually 25-30 psi and suv/trucks are usually 30-35 psi.

That's just my 2 cents...

 

[chuck s]

Passenger car tires have more capacity than needed to ensure a smooth, comfortable ride. Running 44psi is not necessary, makes the contact patch smaller due to a concave profile, and the ride harsh. 44psi is the maximum cold tire pressure. The tires are capable of handling higher pressures, so inflating to 44 (while a waste of time) isn't dangerous.

-- Chuck

 

[kasper]

Well currently I am running 35 psi cold. After driving around for while, I check the psi. The tires are sitting around 38 psi